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Invoke Method in Java

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In Java, java.lang.reflect.*; package is required to import in the program to invoke the methods.

Invoke Method in Java

     

In Java, java.lang.reflect.*; package is required to import in the program to invoke the methods. As you can see here we are using reflect method, this could be either a class method or instance method and the usage of methods in Java is to access a single method either on class or interface. This example will show you, how to declare and invoke the methods in Java. 

 

 

 

 

Code for Java Method - Invoke

import java.lang.reflect.*;

public class InvokeMethod {
public int add(int a, int b)
{
return a + b;
}
public static void main(String args[]){
try {
Class cla = Class.forName("InvokeMethod");
Class partypes[] new Class[2]
partypes[0= Integer.TYPE;
partypes[1= Integer.TYPE;
Method method = cla.getMethod(
"add", partypes);
InvokeMethod invoke = new InvokeMethod();
Object arg[] new Object[3];
arg[0new Integer(30);
arg[1new Integer(40);
arg[2new Integer(50);
Object object = method.invoke(invoke, arg);
Integer integer = (Integer)object;
System.out.println(integer.intValue());
}
catch (Throwable e) {
System.out.println(e);
}
}
}

Output will be displayed as:

Invoke Method Java

Download Source Code

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Posted on: November 15, 2008

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Comments
maurysnake
October 13, 2011
wrong number of arguments

java.lang.IllegalArgumentException: wrong number of arguments the object "arg[]" contains 3 elements and the method add only accept 2 arguments.
deepika
August 28, 2012
code given in download and web page is different

hi , I found that there is a error in the coding given in the web page. things to be corrected. public int add(int a, int b) { return a + b; } change to public int add(int a, int b, int c) { return a + b + c; } Class partypes[] = new Class[2]; change the above to this Class partypes[] = new Class[3]; Add: partypes[2] = Integer.TYPE;
Ask You
August 30, 2012
It's Wrong Code

//Please see the following: import java.lang.reflect.*; public class InvokeMethod { public int add(int a, int b) { return a + b; } public static void main(String args[]){ try { Class cla = Class.forName("InvokeMethod"); Class partypes[] = new Class[2]; partypes[0] = Integer.TYPE; partypes[1] = Integer.TYPE; Method method = cla.getMethod( "add", partypes); InvokeMethod invoke = new InvokeMethod(); Object arg[] = new Object[2]; arg[0] = new Integer(30); arg[1] = new Integer(40); //arg[2] = new Integer(50); Object object = method.invoke(invoke, arg); Integer integer = (Integer)object; System.out.println(integer.intValue()); } catch (Throwable e) { System.out.println(e); } } }
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